Technically, there are not any antelope on Utah’s Antelope Island, the largest island in the Great Salt Lake. Rather, some 200 pronghorn (which fill a similar ecological niche as their Old World counterparts) and 300 mule deer live on the island in the southern part of the lake.
Despite the name (attributed to explorers John Frémont and Kit Carson), Antelope Island is perhaps best known for its free-ranging bison herd. Four breeding pairs were introduced to the island in 1893, a period when hunters had pushed bison toward extinction across much of North America. The lack of trees and abundant grass made the 24 kilometer (15 mile) long and 8 kilometer (5 mile) wide island ideal habitat for the largest land animal in North America. Now, park managers have to remove a few hundred bison every year to keep the population at sustainable levels (between about 500 and 800). See the video below, produced by the Salt Lake Tribune, to learn more about the island’s annual bison roundup.
The landscape and geology of Antelope Island offers much of interest as well. The island is comprised of several different rock formations that represent a range of geological processes. The oldest rocks on the island—gneiss, a coarse-grained, irregularly banded metamorphic rock—formed between two and three billion years ago when sedimentary rocks such as claystone and siltstone were squeezed under extremely high temperatures and pressures. The island’s youngest rocks (tufa limestone) formed when calcium carbonate precipitated from Lake Bonneville about 10,000 to 15,000 years ago.
Ray Boren, a photographer and retired journalist, stopped by the island on December 23, 2015. “I love to go there when I’m out and about,” Boren said in an email. “It is a wonderful rural setting within shouting distance (well, not quite) of the millions of people living along Utah’s Wasatch Front.”
It was a chilly, windy day. “I’ve come to see what’s happening on the island,” Boren told a worker at the park entrance. “You mean, besides the wind?” she replied. Indeed, strong prevailing winds out of the northwest and west were whipping loose snow across the causeway and the island roads, creating intermittent drifts and icy conditions. Even more dramatic was the effect on the island’s shores, benches, plains and mountainous central ridge.
In the photo at the top of the page, originally published by Earth Science Picture of the Day, snow streamed through a boulder field on the island’s northeast side. “The Sun is beginning to set, and the light’s low angle and longer wavelength colors help tint the scene. In the photograph below, snow is being stirred in ephemeral waves, swirls and columns off the jagged terrain of Frary Peak, the island’s highest point at 6,596 feet (2,010 meters).”
For a different perspective on Antelope Island, I dug into the Earth Observatory archives for the images below. Acquired by the Multi-angle Imaging SpectroRadiometer in 2001, the pair offers a winter and summer view of the island. In addition to the obvious difference in snow cover, note the contrasting water color in the northern and southern part of Great Salt Lake. The different colors are the result of a rock-filled causeway built in 1953 to support a permanent railroad. The causeway decreased circulation between the two arms, producing higher salinity on the northern side. If you look closely at the full resolution image, you should be able to see the causeway connecting the island to the mainland.